WASHINGTON — The still-emerging Tea Party movement is not merely waging war against the Republican establishment this year. Some of its more heated disputes are coming from within.

That struggle is playing out vividly in Nebraska, which will hold a Republican Senate primary on Tuesday between former State Treasurer Shane Osborn and Ben Sasse, the president of Midland University.

Mr. Osborn, who has the support of activists in the state, secured a major endorsement last November from FreedomWorks, the organization that helped vault the Tea Party to prominence. Mr. Osborn, the group said, stood “with the grass-roots uprising before it was cool.” But in March, FreedomWorks rescinded its support of Mr. Osborn and backed Mr. Sasse.

Ever since, Nebraska’s Tea Party members have been battling national Tea Party donor groups.

“We are not million-dollar Washington, D.C., special interest groups with strong ties to Capitol Hill. We are simply Nebraskans who are fed up,” a group of 52 activists wrote in an open letter protesting FreedomWorks’s about-face, adding, “We were not consulted, polled, or contacted by these Washington, D.C., groups.”

Other activists complain that the Washington groups are losing touch with people at the local level.

“It worked well when they communicated with us on the ground,” Patrick Bonnett, chairman of the Conservative Coalition of Nebraska, said of the Washington groups. “It breaks down when they unilaterally get involved in our local races, even if it’s in federal campaigns, and endorse and start spending money.”

In many ways, the tensions are an inevitable product of a political movement that began without central leadership and spread with antigovernment fervor.

Initially, the national groups saw themselves as shepherds of a grass-roots Tea Party flock, but they have since taken on an electoral role, cultivating candidates and choosing sides. But they have struggled to come up with candidates at times, and some of their contenders have stumbled badly.

Some of the groups have also engaged in the kind of spending that Tea Party members have denounced.

For instance, the Conservative Campaign Committee paid Diana Nagy, who sings at Tea Party rallies, $4,500 to cover her stay at a Michigan golf resort. The Senate Conservatives Fund, a group founded by former Senator Jim DeMint, Republican of South Carolina, began renting a Capitol Hill townhouse with a hot tub and wine cellar.

There is also widespread criticism that the groups spend a small portion of the money they raise in support of candidates. “The pursuit of money was more important than the desire to work closely with the state activists,” said Dick Armey, a former House majority leader who left FreedomWorks and criticized what he said was the group’s drift.

The groups’ leaders defend their operations. “We need to raise money to keep ourselves going,” said Adam Brandon, the executive vice president of FreedomWorks. “Grass-roots activism is not cheap, and this stuff is not for free.”

In recent weeks, the chosen candidates of groups like FreedomWorks, the Senate Conservatives Fund and the Club for Growth have shown the limits of raw conservative appeal.

In Kentucky, businessman Matt Bevin won the groups’ backing in his primary run against Senator Mitch McConnell, in large part because of their anger over Mr. McConnell’s support for the 2008 Wall Street bailout. It turned out Mr. Bevin backed the bailout as well.

In Kansas, Washington groups helped lift Milton Wolf’s long-shot campaign to defeat Senator Pat Roberts, only to see the campaign of Mr. Wolf, a radiologist, founder when it emerged that he had posted graphic X-rays of gunshot victims on his Facebook page.

In North Carolina, FreedomWorks backed Greg Brannon, an obstetrician, as the Republican to challenge Kay Hagan, the embattled Democratic senator. In February, a jury found that Mr. Brannon had misled two investors in his start-up company and ordered him to pay at least $250,000 in compensation. Last Tuesday, he was defeated by the establishment’s pick, Thom Tillis, North Carolina’s speaker of the House.

And in Mississippi, a clip surfaced from a radio show in which State Senator Chris McDaniel, the Tea Party challenger to Senator Thad Cochran, riffed on picking up Mexican women by calling them “mamacitas.”

“This guy’s been elected for over five years as a state elected official. That matters,” said Chris Chocola, president of Club for Growth, which stood by its investment in Mr. McDaniel. “I would ask the Cochran folks, ‘If this is so inappropriate, then how come you don’t use it’ ” in the campaign in Mississippi?

These issues, particularly the challenges to sitting senators, have unnerved many of the faithful. “They strayed from their plan,” said Victor Mavar, an 87-year-old retired seafood processor from Biloxi, Miss., who said he was a “charter member” of the Club for Growth but wrote a letter to Mr. Chocola to withdraw his support because it had targeted Mr. Cochran.

The groups, he said, should focus on taking out Democrats, not fellow Republicans. Mr. Cochran, he said, “is honest, he is truthful — we’re not going to give him up.”

Republican leaders in Washington hope Mr. Mavar’s view is widely held as they move to starve groups like the Senate Conservatives Fund of contributions.

Speaker John A. Boehner of Ohio and Mr. McConnell, the Senate Republican leader, have vowed to bring about the groups’ demise in the 2014 campaign. Privately, Republican leaders have pointed to possible financial mismanagement and poor candidate vetting to raise doubts among the groups’ small circle of donors.

The Senate Conservatives Fund and its adjunct, Senate Conservatives Action, for example, have raised $12.6 million in this campaign cycle but spent only $4.9 million on the candidates they endorsed. Operating expenditures topped $7.4 million.

Republican officials revealed that the fund had paid $50,000 since June for a five-bedroom Capitol Hill house. Federal Election Commission filings show the group has spent more than $15,000 on interior design services and $11,212 on painting and decorating.

Matt Hoskins, head of the Senate Conservatives Fund, said that by the end of the 2012 campaign cycle the group had spent 68 percent of its revenue on endorsed candidates, and that it expected to hit 70 percent by the midterm election in November.

FreedomWorks has raised $1.8 million this campaign season and spent $1.4 million on its own operations; the group Tea Party Express has spent $7.5 million on operations out of $8 million raised.

Club for Growth, in contrast, has raised $5.2 million and spent $536,000 on operations.

“If all we do is raise money and pocket it, they wouldn’t be upset,” Mr. Hoskins said of the Republican establishment. “The reason they’re upset is that we raise money and spend money on our candidates.”

Correction:

An earlier version of this article stated incorrectly the amount Club for Growth, a conservative political group, has spent on operations. It has spent $536,000, not $1.5 million.

Derek Willis contributed reporting.

A version of this article appears in print on , on Page A12 of the New York edition with the headline: Local Tea Party Activists See Own Groups Among Washington Adversaries. Order Reprints | Today’s Paper | Subscribe